The present invention relates to a peelable laminate comprising a moisture-curable silicone pressure sensitive adhesive (SPSA) releasably adhered to a release liner.
Whether the SPSA has the form of, for example, an adhesive layer on a substrate in the form of a roll of tape; an adhesive layer on an article protected with a peelable backing, such as a decorative trim item to be adhered to an automobile or a structural item to be adhered to a building; or an adhesive film protected on two surfaces by peelable backings, the SPSA must be separated from at least one adjacent surface before it can be used for its intended purpose.
By the term "silicone pressure sensitive adhesive" it is meant an adhesive comprising one or more siloxane components and possessing sufficient tack and cohesive strength so that it can be adhered with mild pressure to a clean stainless steel substrate and then removed therefrom and adhered to the same or another clean substrate. By the term "permanent adhesive" it is meant an adhesive that bonds to a clean substrate and cannot be so removed and thereafter readhered.
Durable structural glazing is currently done with silicone sealants in a multi-step, labor-intensive time-consuming process. Significant improvements in the structural glazing process could be realized if a SPSA were used in place of the silicone sealant in the current process. Unfortunately, standard SPSAs are not completely suitable for structural glazing applications because of their inherent flowability, albeit slow in the recently improved SPSAs, under sustained stress. Under the sustained stress of gravity the heavy glass panel that is currently used in structural glazing, if not further supported, would eventually experience shear failure of a SPSA bond. A SPSA that cures to a non-shearing adhesive having high adhesive strength would be very beneficial in this and other applications.
In co-pending applications for U.S. patent, titled "SOLUTION-STABLE, MOISTURE-CURABLE SILICONE PRESSURE SENSITIVE ADHESIVES" and "STABLE, MOISTURE-CURABLE SILICONE PRESSURE SENSITIVE ADHESIVES", filed on even date herewith and assigned to the assignee of this application, there are disclosed and claimed moisture-curable SPSA compositions. The use of these SPSA composition would be greatly enhanced if it could be protected in thin film form with a release liner. The disclosures of said patents are incorporated herein by reference to fully delineate these SPSA compositions and how to prepare them.
Recently, Brown and Stickles, U.S. Pat. No. 4,736,048, disclosed a fluorosilicone release liner which is siad to be useful for releasing solvent-cast, heat-cured SPSAs with a force of no more than 200 grams per inch.
Tangney, U.S. Ser. No. 276,178, filed on Nov. 23, 1988 now U.S. Pat. No. 5,082,701 and assigned to the assignee of this application disclosed a laminate article comprising a fluorosilicone release liner and an additioncured SPSA.
Brown and Stickles, and Tangney provided examples of laminates comprising peroxide-cured and addition-cured SPSAs which had been solvent-cast and heat-cured in contact with their fluorosilicone liner. However, they did not disclose any examples of a laminate comprising a moisture-cured SPSA.